Developing apparatus and image forming apparatus that incorporates the developing apparatus

Abstract

A developing apparatus is incorporated in an image forming apparatus. An electrostatic latent image is formed on an image bearing body. A developing member supplies a developer material to the electrostatic latent image. A supplying member supplies the developer material to the developing member. A developer material chamber holds the developer material therein. A layer forming member is provide in the proximity to the supplying member, and forms a layer of the developer material. The layer forming member is positioned such that a gap Δg is defined between the layer forming member and the supplying member. When the supplying member rotates, the surface of the layer forming member applies pressure to the toner on the supplying member to form the layer having a smooth surface not more than 0.5 mm.

1. A developing apparatus comprising:
 an image bearing body on which an electrostatic latent image is formed; 
 a developing member that supplies a developer material to the electrostatic latent image; 
 a supplying member that supplies the developer material to said developing member, the supplying member including a cylindrical surface rotatable and in contact with the developing member; 
 a developer material chamber that holds the developer material therein, the developer material chamber having a first gap formed between the cylindrical surface and a circumferential inner wall surface of the developer material chamber; and 
 a projection that projects from the circumferential inner wall surface of said developer material chamber toward said supplying member, the projection being disposed downstream of the first gap with respect to a rotation of the supplying member, the projection having a first guide surface forming a second gap with the cylindrical surface of the supplying member, the second gap being smaller than the first gap and not more than 0.5 mm. 
 
     
     
       2. The developing apparatus according to  claim 1 , wherein said projection is formed in one piece with said developer material chamber. 
     
     
       3. The developing apparatus according to  claim 1 , wherein said projection is bonded to the circumferential inner wall surface of said developer material chamber. 
     
     
       4. The developing apparatus according to  claim 1 , wherein said projection is supported by a supporting member that supports said supplying member. 
     
     
       5. The developing apparatus according to  claim 1 , wherein said supplying member includes a diameter larger nearer a longitudinally middle portion of said supplying member; and
 wherein said projection extends substantially parallel to said supplying member and the first guide surface extends such that the first guide surface is configured to mate with an outer contour of said supplying member while maintaining the second gap. 
 
     
     
       6. The developing apparatus according to  claim 1 , wherein said supplying member includes a diameter larger nearer a longitudinally middle portion of said supplying member; and
 wherein said projection extends substantially parallel to said supplying member and the first guide surface extends such that the second gap is larger in the vicinity of longitudinal end portions of said supplying member than in a middle portion of said supplying member. 
 
     
     
       7. The developing apparatus according to  claim 1 , wherein said supplying member includes a diameter larger nearer a longitudinally middle portion of said supplying member; and
 wherein said projection is mounted to a mounting member supported on a supporting member that supports said supplying member, the mounting member being movable relative to the supporting member. 
 
     
     
       8. The developing apparatus according to  claim 7 , wherein the mounting member is one of two mounting members disposed in the vicinity of longitudinal end portions of said supplying member, each one of said mounting members includes a plurality of fitting engagement portions, wherein the plurality of fitting engagement portions are provided such that center-to-center distances between the plurality of fitting engagement portions and said supplying member are different from one another. 
     
     
       9. The developing apparatus according to  claim 1 , wherein said developing apparatus is incorporated in an image forming apparatus, the image forming apparatus comprising:
 an exposing unit that illuminates a charged surface of said image bearing body to form an electrostatic latent image; 
 a transfer unit that transfers a visible image from said image bearing body onto a print medium; 
 a fixing unit that fixes the visible image on the print medium; and 
 a transport unit that transports the print medium. 
 
     
     
       10. The developing apparatus according to  claim 1 , wherein said projection is spaced apart from said supplying member by a predetermined gap. 
     
     
       11. A developing apparatus comprising:
 an image bearing body on which an electrostatic latent image is formed; 
 a developing member that supplies a developer material to the electrostatic latent image; 
 a supplying member that supplies the developer material to said developing member, the supplying member including a cylindrical surface rotatable and in contact with the developing member; 
 a developer material chamber that holds the developer material therein, the developer material chamber having a first gap formed between the cylindrical surface and a circumferential inner wall surface of the developer material chamber; and 
 a projection that projects from the circumferential inner wall surface of said developer material chamber toward said supplying member, the projection being disposed downstream of the first gap with respect to a rotation of the supplying member, the projection having:
 a first guide surface forming a second gap with the cylindrical surface of the supplying member, the second gap being smaller than the first gap, and 
 a second guide surface disposed between the first guide surface and the circumferential inner surface and contiguous with the first guide surface and the circumferential inner wall surface, the second guide surface guides the developer material in the first gap into the second gap as the supplying member rotates. 
 
 
     
     
       12. The developing apparatus according to  claim 11 , wherein said projection is formed in one piece with said developer material chamber. 
     
     
       13. The developing apparatus according to  claim 11 , wherein said projection is bonded to the circumferential inner wall surface of said developer material chamber. 
     
     
       14. The developing apparatus according to  claim 11 , wherein said projection is supported by a supporting member that supports said supplying member. 
     
     
       15. The developing apparatus according to  claim 11 , wherein said supplying member includes a diameter larger nearer a longitudinally middle portion of said supplying member; and
 wherein said projection extends substantially parallel to said supplying member and the first guide surface extends such that the first guide surface is configured to mate with an outer contour of said supplying member while maintaining the second gap. 
 
     
     
       16. The developing apparatus according to  claim 11 , wherein said supplying member includes a diameter larger nearer a longitudinally middle portion of said supplying member; and
 wherein said projection extends substantially parallel to said supplying member and the first guide surface extends such that the second gap is larger in the vicinity of longitudinal end portions of said supplying member than in a middle portion of said supplying member. 
 
     
     
       17. The developing apparatus according to  claim 11 , wherein said supplying member includes a diameter larger nearer a longitudinally middle portion of said supplying member; and
 wherein said projection is mounted to a mounting member supported on a supporting member that supports said supplying member, the mounting member being movable relative to the supporting member. 
 
     
     
       18. The developing apparatus according to  claim 17 , wherein the mounting member is one of two mounting members disposed in the vicinity of longitudinal end portions of said supplying member, each one of said mounting members includes a plurality of fitting engagement portions, wherein the plurality of fitting engagement portions are provided such that center-to-center distances between the plurality of fitting engagement portions and said supplying member are different from one another. 
     
     
       19. The developing apparatus according to  claim 11 , wherein said developing apparatus is incorporated in an image forming apparatus, the image forming apparatus comprising:
 an exposing unit that illuminates a charged surface of said image bearing body to form an electrostatic latent image; 
 a transfer unit that transfers a visible image from said image bearing body onto a print medium; 
 a fixing unit that fixes the visible image on the print medium; and 
 a transport unit that transports the print medium. 
 
     
     
       20. The developing apparatus according to  claim 11 , wherein said projection is spaced apart from said supplying member by a predetermined gap.